Improvement in cast-iron ordnance



UNITED STATES PATENT OFFICE.,

JOHN A. -DAHLGREN, OF PHILADELPHIA, PENNSYLVANIA'.

IMPROVEMENT IN CAST-l RON ORDNANCE.

Specification forming part of Letters Patent No. 32,985, dated August 6,1861.

To a/ZZ whom it may concern:

Be it known that I, JOHN A. DAHLGREN, of the city and county ofPhiladelphia, in the State of Pennsylvania, have invented certain newand useful Improvements in the Manufacture of Cast-Iron Ordnance, ofwhich the following is a full, clear, and exact description, referencebeing had to accompanying drawings, which make part of thisspeciiication, in which--l Figure l represents a side elevation of a gunembracing my improvement. Fig. 2 represents a similar view of the bodyof the gun, the trunnions, cascabel, and their supports being detached.Fig. 3 represents the pattern for casting the-gun, which is both longerand of greater diameter than the iinished gun. Fig. 4 represents a sideelevation ofthe breechstrap, band, trunnions, and cascabel detached fromthe gun. Fig. 5 represents a top View of the same. Fig. 6 represents aview ofthe same, looking at the front of the trunnions and band.

The improvement which is claimed' under this patent consists in castingthe cannon without cascabel or trunnions, the object being thus tosecure, as far as a symmetrical form free from protuberances will attainsuch objects, uniformity in the texture and strength of metal throughoutthe whole mass of the gun, which should therefore be cast of asymmetrical form without any angles and as nearly as may be of equaldiameters, but if not of equal diameters,then of gradual taper, thatitit may cool simultaneously and regularly throughout, and thereby avoidthe inequalities of texture and strength that result from irregularcooling and contractile strains. The pattern for casting is made afterthe form shown in Fig. 3, and is molded in the usual' manner, exceptthat the patterns for the cas-v cabel and trunnions are omitted. Whenthe gun has been reduced to the proper proportion and bored, the slightswell a at the base.

of the breech is notched, as seen in Fig. 2, so as to receive thetrunnionstrap b. This notch prevents the rotation of the gun in thestraps from the reaction of the projectile when it receives its rotarymotion from the rifle of the bore. This strap embraces the rear of thecannon from the base of the breech to the locality of the trunnions c c,which,vas well as the cascabel d, I prefer to make in one piece with thetrunnion-strap, together with asemicircular band, e, to encompass thelower half of the gun. A section is omitted from the upper side of thetrunnions c c, which is supplied by separate pieces c c', attached to asemicircular ban d, f, intended to clasp the upper half ofthe cannon.The parts c c', being adjusted so as to fit the lower parts, c c, of thetrunnions, are secured to them by stout bolts passing through both theparts. rIhe trunnions and their strap should be made of the best bronzegun-metal. The cascabel is to be pierced, and a screw-threadcut toreceive the elevating-screw. t Thelock and'back sight are to be attachedby small straps or brackets of metal to the trunnion strap These smallstraps or brackets may be connected to the trunnion-strap by screws orrivets.

In the making of wroughtiron ordnance, 1

the trunnions have been applied by forging them to a band,which was thenshrunk upon the body of the gun, which it compressed with great force,to produce the requisite adhesion for a rm connection of the trunnionsto the gun; but this differs fromthe improved mode herein described,which secures the trunnions in place independently of any adhesion ofthe band to the surfaceof the gun, or any compression of the gun by theband ythat would interfere with the waves of expansion or vibrationproduced in the gun by the explosion of its charge.

What I claim as my invention is- 'A gun having a body cast without-trunnions or cascabel, so as to obtain the condition of metal mostfavorable to strength, the trunnions and other accessories requiredioroperating the gun being secured to its surface by means of atrunnion-strap and band or the equivalentthereof, substantially asdescribed.

In testimony whereof I have hereunto subscribed my name.

J NO. A. DAHLGREN. Witnesses:

A. B. NORTON, J No. D. BRANDT.

